Nanoscale patterning of complex magnetic nanostructures by reduction with low-energy protons

Abstract

Techniques that can produce patterns with nanoscale details on surfaces have a central role in the development of new electronic, optical and magnetic devices and systems. High-energy ion irradiation can produce nanoscale patterns on ferromagnetic films by destroying the structure of layers or interfaces, but this approach can damage the film and introduce unwanted defects. Moreover, ferromagnetic nanostructures that have been patterned by ion irradiation often interfere with unpatterned regions through exchange interactions, which results in a loss of control over magnetization switching. Here, we demonstrate that low-energy proton irradiation can pattern an array of 100-nm-wide single ferromagnetic domains by reducing [Co(3)O(4)/Pd](10) (a paramagnetic oxide) to produce [Co/Pd](10) (a ferromagnetic metal). Moreover, there are no exchange interactions in the final superlattice, and the ions have a minimal impact on the overall structure, so the interfaces between alternate layers of cobalt (which are 0.6 nm thick) and palladium (1.0 nm) remain intact. This allows the reduced [Co/Pd](10) superlattice to produce a perpendicular magnetic anisotropy that is stronger than that observed in the metallic [Co/Pd](10) superlattices we prepared for reference. We also demonstrate that our non-destructive approach can reduce CoFe(2)O(4) to metallic CoFe.

Influence of elastically pinned magnetic domain walls on magnetization reversal in multiferroic heterostructures

“…Strong local pinning of magnetic domain walls can be attained by various methods, including focused ion beam or low-energy proton irradiation [4][5][6][7][8][9][10] and oxygen ion migration from an adjacent metal-oxide layer [11,12]. Other promising strategies to locally tailor the magnetic properties of a continuous magnetic medium exploit either exchange coupling with a multiferroic BiFeO 3 layer [13][14][15][16] or strain coupling to the ferroelastic domains of a ferroelectric BaTiO 3 substrate * sebastiaan.van.dijken@aalto.fi [17][18][19][20][21][22][23].…”

Effect of Proton Irradiation on the Magnetic Properties of Antiferromagnet/ferromagnet Structures

“…The exchange bias is increased by a postannealing step, most likely due to the enhanced interfacial structures. A recent report demonstrates that proton irradiation can modify the magnetic property of FM/nonmagnetic samples of Co/Pd multilayer structures [11,12]. The proton irradiation to the CoO/Pd sample causes the reduction of the CoO to become a metallic Co, thus develop- In this study, we utilize proton irradiation on an AFM/ FM bilayer and investigate its effect on the magnetic properties of the exchange bias and on the magneto-thermoelectric properties.…”

Study on Proton Radiation Resistance of 410 Martensitic Stainless Steels under 3 MeV Proton Irradiation

“…However, the radiation effects on the magnetic properties of the 410 stainless steels, which are crucial for the application of 410 stainless steels in the in-vessel magnetic cores, are not investi- In this work, we have investigated the effects of proton irradiation on the magnetic properties of 410 stainless steels in order to understand the correlation between irradiation damage and magnetic property degradation. Proton irradiation was used to simulate neutron irradiation since it imparts same damages as neutron irradiation and also can provide short irradiation time and high damage rate [9,10]. And also, the penetration depth and transmutation in proton irradiation is very less [11,12].…”